What is Quick Charge?

A. HOW QUICK CHARGE (QC) WORKS?

Quick Charge is a charging technology found in Qualcomm SoCs, used in devices such as mobile phones, for managing power delivered over USB ports. It offers more power and thus charges batteries in devices faster than standard USB rates allow.

B. THEN, HOW FAST IS QC3.0, AS COMPARED TO OLDER GENERATIONS OF QC2.0?

QC 3.0 is a charging protocol designed by Qualcomm, it offers stepless multi-voltage charging from 3.7V to 20V; your device can receive the perfect voltage and current optimized to its exact charging state

As you could see from the above picture, in terms of power output, QC 3.0 is not much different from QC 2.0 to be frank, however, they are not the same in these ways;

QC 2.0 multi-voltage is fixed at 5, 9, 12 and 20V. This fixed voltage means the charging is done in voltage stages.

QC 3.0 can change exact voltage and can be anywhere between 3.7 and 20v, the charging is variable and this increases the overall efficiency of the charge.

QC 2.0 jumps in stages, less efficient but still enhances speed.

Standard fast charge stays at 5V and provides a slower charge.

The advantage of QC 3.0 is that it can provide optimal voltage at the precise need of the battery, so during charging you are always at the fastest charging voltage. Simply, we can put it this way;

3.0 IS SMARTER

THE VARIABLE VOLTAGE DELIVERS FASTER CHARGE WITH THE SAME POWER.;

C. AND, PEOPLE ARE TALKING ABOUT QC4.0, WHAT'S NEW WITH IT?

First of all, please see the picture below which shows the evolution of Quick Charge from 1.0 to 4.0;

Quick Charge 4.0 was announced by Qualcomm in November, 2016, which brings three major improvements. The first is 'Dual charge' which divides the charge current across two power management ICs. Qualcomm says this should result in reduced charge time (approximately 15%).

The second new feature of QC 4.0 is 'Intelligent Thermal Balancing' which moves the electric current through the coolest path automatically, eliminating potential hot spots. Finally, QC 4.0 includes a handful of new safety features, such as monitoring both the device case and connector temperature levels at the same time.

D. HOW IS QC4.0 BETTER THAN QC3.0?

It charges faster of course, and more, it’s designed to be more efficient and run cooler than the prior generations. Compared to Quick Charge 3.0, Quick Charge 4.0 is up-to 20 percent faster, or 30 percent more efficient, while charging up to 5° C cooler.

In terms of Power Output, QC 3.0 is fast charge of 18W, while QC 4.0 is using a quick charging scheme of 28W. Also, according to Qualcomm, QC 4.0 has a Dual Charge technology over QC 3.0.

E. HOW CAN I ENJOY THE ADVANCEMENT BY QC4.0?

To give you a better sense of this, Qualcomm adopted a new measurement that helps sum it up simply. Qualcomm promises QC 4.0 would bring up to 20% faster charging speeds all while charging at temperatures that are 5° C cooler. In testing the standard on a reference device (with a 2,750mAh battery), Qualcomm says that it achieved speeds fast enough to promise a “5 for 5”.

That’s to say, users can plug their phones in for 5 minutes to get 5 hours worth-of-power. For longer charging sessions, Quick Charge 4.0 is capable of charging up to 50% capacity in just 15 minutes, however, results will vary if you have a larger battery, yes, this is the catch.

F. HOW TO DIFFERENTIATE QC AND USB-C POWER DELIVERY?

Well, both the Quick Charge from Qualcomm and USB Power Delivery from the USB-IF standards are the most common used protocols. While, these are the major differences;

1. The language they speak;

USB-PD is an entirely different language than QC 2.0 / 3.0 / 4.0. They negotiate and handle power differently from each other. If you plug USB-PD into a QC device it should default to 5V, 1 or 2 amp standard charging.

2. Quick charge is a proprietary technology, while USB Power Delivery is a standard protocol from the USB-IF standards organization

QC allows charging of battery powered devices, primarily mobile phones, at levels above and beyond the typical 5 volts and 2 amps which most USB standards allow for. To take advantage of Qualcomm Quick Charge, both the host providing power and the device must support it.

USB-PD can be implemented over any USB connection, but requires new connectors and cables for full USB 2.0 connector support. By comparison, Power Delivery can support voltages as high as 20V, and can support charging at up to 100W max.

3. Also, it depends on what devices you are using

It seems that USB-PD can deliver a much higher power output, but actually most current smartphones do not need more than 18w charging, that’s why Qualcomm’s Quick Charge is widely adopted by most of smartphones, while Power Delivery as a standard that anyone can use is more designed for larger devices like laptops and household appliances.

However, things changed with the introduction of QC 4.0

Qualcomm announced Quick Charge 4.0 in 2016 which is compatible with Power Delivery. In other words, Quick Charge 4.0 has simply learned to speak PD language now.

G. THEN, HOW DO PD AND QUICK CHARGE 4.0 WORK TOGETHER?

As explained above, Quick Charge 4.0 is compatible with Power Delivery, which raises the question of what Quick Charge 4.0 brings to the table as, Power Delivery is already proficient in technologies for negotiating current and voltage.

Qualcomm’s Quick Charge 4.0 can intervene to take control with regard to the device’s so-called thermal budget; in other words: It makes sure that the smartphone does not get too hot when charging. The fact that Quick Charge and USB-PD can co-exist is due to the fact that Power Delivery is solely a protocol for negotiating voltage and current. Quick Charge 4.0 has simply learned to speak this language, but does the same thing as Quick Charge 3.0 with a few upgrades. Thus, Quick Charge 4.0 is exclusive to Type-C.

Qualcomm's Quick Charge 4.0 can intervene to take control with regard to the device's so-called thermal budget; in other words: It makes sure that the smartphone does not get too hot when charging. The fact that Quick Charge and UsB-PD can co-exist is due to the fact that Power Delivery is solely a protocol for negotiating voltage and current. Quick Charge 4.0 has simply learned to speak this language, but does the same thing as Quick Charge 3.0 with a few upgrades. Thus, Quick Charge 4.0 is exclusive to Type-C.